Tiêu đề 27 JUNE PAPER.pdf ✅

27. In any Bohr orbit of hydrogen atom, the ratio of kinetic energy to potential energy of the electron is (A) 1/2 (B) 2 (C) –1/2 (D) –2 28. A proton and an -particle are accelerated through a potential difference of 100 V. The ratio of the wavelength associated with the proton to that associated with an -particle is (A) 2 :1 (B) 2 : 1 (C) 2 2 :1 (D) 1 :1 2 2 29. In a radioactive substance at t = 0, the number of atoms is 8 × 10 4 . Its half life period is 3 year. The number of atoms 1 × 104 will remain after an interval of (A) 9 year (B) 8 year (C) 6 year (D) 24 year 30. 92U238 on absorbing a neutron goes over to 92U239 . This nucleus emits an electron to go over to Neptunium which on further emitting an electron goes over to Plutonium. The resulting Plutonium can be expressed as (A) 94Pu239 (B) 92Pu239 (C) 93Pu240 (D) 92Pu240 31. If T is half-life of a radioactive material, the fraction that would remain after a time T/2 is (A) 1/2 (B) 1/ 2 (C) 3/4 (D) 2 1 2  32. The average binding energy per nucleon in the nucleus of an atom is approximately (A) 8 eV (B) 8 MeV (C) 8 kev (D) 8 Volt 33. In the decay series A A A 4 A 4 z z 1 z 1 z 1 X Y R R         the emitted particles, respectively, will be (A) , ,  (B) , , (C) , ,  (D) , ,  34. The particle which is deflected by electric field is (A) -rays (B) X-rays (C) Neutrons (D) -particles. 35. If 10% of a radioactive material decays in 5 days, the amount of original material left after 20 days is approximately (A) 35% (B) 45% (C) 55% (D) 65% 36. In the nuclear reaction 85X297 Y + 4, Y is (A) 77Y281 (B) 77Y285 (C) 81Y293 (D) 81Y281 37. A heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio 8 : 1. The ratio of radii of the fragments is (A) 1:2 (B) 1:4 (C) 4:1 (D) 2:1 38. A nuclear reaction is given as 41H1 → 2He4 + 0e 1 + energy. Mention the type of reaction. (A) fusion (B) fission (C) just chemical reaction (D) none of these. 39. If Mo is the mass of an oxygen isotope 8O 17, MP and MN are the masses of a proton and a neutron respectively, the nuclear binding energy of the isotope is (A) (M0 – 17 MN) C2 (B) (M0 – 8 MP)C2 (C) (M0 – 8 MP – 9 MN) C2 (D) M0 – C 2 40. On bombarding U235 by slow neutron, 200 MeV energy is released. If the power output of atomic reactor is 1.6 MW, then the rate of fission will be (A) 8 × 1016 /s (B) 20 × 1016/s (C) 5 × 1022 /s (D) 5 × 1016 /s 41. Binding energy per nucleon vs. mass number curve for nuclei is shown in the figure. W, X, Y and Z are four nuclei indicated on the curve. The process that would release energy is (A) Y → 2Z (B) W→ X + Z (C) W  2Y (D) X → Y + Z. 42. For uranium nucleus how does its mass vary with volume? (A) m  V (B) m  1/ V (C) m v  (D) m  V2 43. A particle of mass M at rest decays into two particles of masses m1 and m2, having non-zero velocities. The ratio of the de-Broglie wavelengths of the particles, 1/2 is (A) m1/m2 (B) m2/m1 (C) 1 : 1 (D) m / m 2 1